How to use the pypeline.core.arrows.function_arrow.FunctionArrow function in Pypeline

def test(arrow):
    if not isinstance(arrow, FunctionArrow):
        raise ValueError("Must be a FunctionArrow")

    # (a &&& arr id) >>> arr (\(b, x) = if b then Left x else Right x)
    return (arrow & FunctionArrow(lambda x: x)) >> FunctionArrow(lambda t: Left(t[1]) if t[0] else Right(t[1])) 

def if_maker(predicate_func, then_func, else_func):
    return test(FunctionArrow(predicate_func)) >> (FunctionArrowChoice(then_func) | FunctionArrowChoice(else_func))

def test(arrow):
    if not isinstance(arrow, FunctionArrow):
        raise ValueError("Must be a FunctionArrow")

    # (a &&& arr id) >>> arr (\(b, x) = if b then Left x else Right x)
    return (arrow & FunctionArrow(lambda x: x)) >> FunctionArrow(lambda t: Left(t[1]) if t[0] else Right(t[1]))

# (at your option) any later version.
#
# Pypeline is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with Pypeline.  If not, see .
#
from pypeline.core.arrows.arrow import Arrow, ArrowChoice
from pypeline.core.arrows.function_arrow import FunctionArrow
from pypeline.core.types.either import *


class FunctionArrowChoice(ArrowChoice, FunctionArrow):
    def __init__(self, f):
        ArrowChoice.__init__(self)
        FunctionArrow.__init__(self, f)

    #
    # left :: a b c -> a (Either b d) (Either c d)
    #
    #                +-------------------+
    #                |    /--- f ---\    |
    # Either b d --->+---(           )---+---> Either c d
    #                |    \---------/    |
    #                +-------------------+
    def left(self):
        def left_func(either):
            if isinstance(either, Left):
                return Left(self._func(either.val))

def __or__(self, other):
        if not isinstance(other, FunctionArrowChoice):
            raise ValueError("Must be a FunctionArrowChoice")

        def merge(either):
            if not isinstance(either, Either):
                raise ValueError("Must be an Either")
            return either.val

        return (self + other) >> FunctionArrow(merge)

def __init__(self, f):
        ArrowChoice.__init__(self)
        FunctionArrow.__init__(self, f)