How to use the quantities.constants._utils._cd function in quantities

"""
"""
from __future__ import absolute_import

from ._utils import _cd
from ..unitquantity import UnitConstant


m_t = triton_mass = UnitConstant(
    'triton_mass',
    _cd('triton mass'),
    symbol='m_t'
)
g_t = triton_g_factor = UnitConstant(
    'triton_g_factor',
    _cd('triton g factor'),
    symbol='g_t'
)
mu_t = triton_magnetic_moment = UnitConstant(
    'triton_magnetic_moment',
    _cd('triton magnetic moment'),
    symbol='mu_t',
    u_symbol='μ_t'
)
triton_mass_energy_equivalent = UnitConstant(
    'triton_mass_energy_equivalent',
    _cd('triton mass energy equivalent'),
    symbol='(m_t*c**2)',
    u_symbol='(m_t·c²)'
)
triton_mass_energy_equivalent_in_MeV = UnitConstant(
    'triton_mass_energy_equivalent_in_MeV',

u_symbol='(e⁴·a₀⁴/E_h³)'
)
hbar = atomic_unit_of_action = UnitConstant(
    'atomic_unit_of_action',
    _cd('atomic unit of action'),
    symbol='hbar',
    u_symbol='ħ'
)
atomic_unit_of_charge = UnitConstant(
    'atomic_unit_of_charge',
    _cd('atomic unit of charge'),
    symbol='e'
)
atomic_unit_of_charge_density = UnitConstant(
    'atomic_unit_of_charge_density',
    _cd('atomic unit of charge density'),
    symbol='(e/a_0**3)',
    u_symbol='(e/a₀³)'
)
atomic_unit_of_current = UnitConstant(
    'atomic_unit_of_current',
    _cd('atomic unit of current'),
    symbol='(e*E_h/hbar)',
    u_symbol='(e·E_h/ħ)'
)
atomic_unit_of_electric_dipole_moment = UnitConstant(
    'atomic_unit_of_electric_dipole_moment',
    _cd('atomic unit of electric dipole moment'),
    symbol='(e*a_0)',
    u_symbol='(e·a₀)'
)
atomic_unit_of_electric_field = UnitConstant(

"""
from __future__ import absolute_import

from ._utils import _cd
from ..unitquantity import UnitConstant


natural_unit_of_action = UnitConstant(
    'natural_unit_of_action',
    _cd('natural unit of action'),
    symbol='hbar',
    u_symbol='ħ'
)
natural_unit_of_energy = UnitConstant(
    'natural_unit_of_energy',
    _cd('natural unit of energy'),
    symbol='(m_e*c**2)',
    u_symbol='(mₑ·c²)'
)
natural_unit_of_length = UnitConstant(
    'natural_unit_of_length',
    _cd('natural unit of length'),
    symbol='lambdabar_C',
    u_symbol='ƛ_C'
)
natural_unit_of_mass = UnitConstant(
    'natural_unit_of_mass',
    _cd('natural unit of mass'),
    symbol='m_e',
    u_symbol='mₑ'
)
natural_unit_of_momentum = UnitConstant(

# -*- coding: utf-8 -*-
"""
"""
from __future__ import absolute_import

from ._utils import _cd
from ..unitquantity import UnitConstant


molar_Planck_constant = UnitConstant(
    'molar_Planck_constant',
    _cd('molar Planck constant'),
    symbol='(N_A*h)',
    u_symbol='(N_A·h)'
)
molar_Planck_constant_times_c = UnitConstant(
    'molar_Planck_constant_times_c',
    _cd('molar Planck constant times c'),
    symbol='(N_A*h*c)',
    u_symbol='(N_A·h·c)'
)
h = Planck_constant = UnitConstant(
    'Planck_constant',
    _cd('Planck constant'),
    symbol='h'
)
hbar = Planck_constant_over_2_pi = UnitConstant(
    'Planck_constant_over_2_pi',

molar_Planck_constant = UnitConstant(
    'molar_Planck_constant',
    _cd('molar Planck constant'),
    symbol='(N_A*h)',
    u_symbol='(N_A·h)'
)
molar_Planck_constant_times_c = UnitConstant(
    'molar_Planck_constant_times_c',
    _cd('molar Planck constant times c'),
    symbol='(N_A*h*c)',
    u_symbol='(N_A·h·c)'
)
h = Planck_constant = UnitConstant(
    'Planck_constant',
    _cd('Planck constant'),
    symbol='h'
)
hbar = Planck_constant_over_2_pi = UnitConstant(
    'Planck_constant_over_2_pi',
    _cd('Planck constant over 2 pi'),
    symbol='(h/(2*pi))',
    u_symbol='ħ'
)
quantum_of_circulation = UnitConstant(
    'quantum_of_circulation',
    _cd('quantum of circulation'),
    symbol='(h/(2*m_e))',
    u_symbol='(h/(2·mₑ))'
)
quantum_of_circulation_times_2 = UnitConstant(
    'quantum_of_circulation_times_2',

_cd('Bohr magneton in K/T')
)

electron_mass_energy_equivalent = UnitConstant(
    'electron_mass_energy_equivalent',
    _cd('electron mass energy equivalent'),
    symbol='(m_e*c**2)',
    u_symbol='(mₑ·c²)'
)
electron_mass_energy_equivalent_in_MeV = UnitConstant(
    'electron_mass_energy_equivalent_in_MeV',
    _cd('electron mass energy equivalent in MeV')
)
electron_mass_in_u = UnitConstant(
    'electron_mass_in_u',
    _cd('electron mass in u')
)
electron_molar_mass = UnitConstant(
    'electron_molar_mass',
    _cd('electron molar mass'),
    symbol='M_e',
    u_symbol='Mₑ'
)

electron_deuteron_mass_ratio = UnitConstant(
    'electron_deuteron_mass_ratio',
    _cd('electron-deuteron mass ratio'),
    symbol='(m_e/m_d)',
    u_symbol='(mₑ/m_d)'
)
electron_muon_mass_ratio = UnitConstant(
    'electron_muon_mass_ratio',

_cd('proton rms charge radius'),
    symbol='R_p'
)
proton_charge_to_mass_quotient = UnitConstant(
    'proton_charge_to_mass_quotient',
    _cd('proton charge to mass quotient'),
    symbol='(e/m_p)'
)
g_p = proton_g_factor = UnitConstant(
    'proton_g_factor',
    _cd('proton g factor'),
    symbol='g_p'
)
gamma_p = proton_gyromagnetic_ratio = UnitConstant(
    'proton_gyromagnetic_ratio',
    _cd('proton gyromagnetic ratio'),
    symbol='gamma_p',
    u_symbol='γ_p'
)
proton_gyromagnetic_ratio_over_2_pi = UnitConstant(
    'proton_gyromagnetic_ratio_over_2_pi',
    _cd('proton gyromagnetic ratio over 2 pi'),
    symbol='(gamma_p/(2*pi))',
    u_symbol='(γ_p/(2·π))'
)
mu_p = proton_magnetic_moment = UnitConstant(
    'proton_magnetic_moment',
    _cd('proton magnetic moment'),
    symbol='mu_p',
    u_symbol='μ_p'
)
sigma_prime_p = proton_magnetic_shielding_correction = UnitConstant(

)
alpha = fine_structure_constant = UnitConstant(
    'fine_structure_constant',
    _cd('fine-structure constant'),
    symbol='alpha',
    u_symbol='α'
)
inverse_fine_structure_constant = UnitConstant(
    'inverse_fine_structure_constant',
    _cd('inverse fine-structure constant'),
    symbol='alpha**-1',
    u_symbol='α⁻¹'
)
c_1 = first_radiation_constant = UnitConstant(
    'first_radiation_constant',
    _cd('first radiation constant'),
    symbol='c_1',
    u_symbol='c₁'
)
c_1L = first_radiation_constant_for_spectral_radiance = UnitConstant(
    'first_radiation_constant_for_spectral_radiance',
    _cd('first radiation constant for spectral radiance'),
    symbol='c_1L',
    u_symbol='c₁_L'
)
inverse_of_conductance_quantum = UnitConstant(
    'inverse_of_conductance_quantum',
    _cd('inverse of conductance quantum'),
    symbol='G_0**-1',
    u_symbol='G₀⁻¹'
)
Josephson_constant = K_J = UnitConstant(

'triton_mass_energy_equivalent_in_MeV',
    _cd('triton mass energy equivalent in MeV')
)
triton_mass_in_u = UnitConstant(
    'triton_mass_in_u',
    _cd('triton mass in u')
)
triton_molar_mass = UnitConstant(
    'triton_molar_mass',
    _cd('triton molar mass'),
    symbol='M_t'
)

triton_electron_mass_ratio = UnitConstant(
    'triton_electron_mass_ratio',
    _cd('triton-electron mass ratio'),
    symbol='(m_t/m_e)',
    u_symbol='(m_t/mₑ)'
)
triton_proton_mass_ratio = UnitConstant(
    'triton_proton_mass_ratio',
    _cd('triton-proton mass ratio'),
    symbol='(m_t/m_p)',
    u_symbol='(m_t/m_p)'
)

triton_electron_magnetic_moment_ratio = UnitConstant(
    'triton_electron_magnetic_moment_ratio',
    _cd('triton-electron magnetic moment ratio'),
    symbol='(mu_t/mu_e)',
    u_symbol='(μ_t/μₑ)'
)

symbol='lambda_C_tau',
    u_symbol='ƛ_C_τ'
)
tau_mass_energy_equivalent = UnitConstant(
    'tau_mass_energy_equivalent',
    _cd('tau mass energy equivalent'),
    symbol='(m_tau*c**2)',
    u_symbol='(m_τ·c²)'
)
tau_mass_energy_equivalent_in_MeV = UnitConstant(
    'tau_mass_energy_equivalent_in_MeV',
    _cd('tau mass energy equivalent in MeV')
)
tau_mass_in_u = UnitConstant(
    'tau_mass_in_u',
    _cd('tau mass in u')
)
tau_molar_mass = UnitConstant(
    'tau_molar_mass',
    _cd('tau molar mass'),
    symbol='M_tau',
    u_symbol='M_τ'
)

tau_electron_mass_ratio = UnitConstant(
    'tau_electron_mass_ratio',
    _cd('tau-electron mass ratio'),
    symbol='(m_tau/m_e)',
    u_symbol='(m_τ/mₑ)'
)
tau_muon_mass_ratio = UnitConstant(
    'tau_muon_mass_ratio',