How to use the pymarc.leader.Leader function in pymarc

def test_getters(self):
        leader = Leader(LEADER)
        for field, index, expected in FIELDS:
            self.assertEqual(getattr(leader, field), leader[index])
            self.assertEqual(expected, leader[index])

def test_add(self):
        leader = Leader(LEADER)
        new_leader = leader[0:9] + "b" + leader[10:]
        self.assertEqual(new_leader, "00475casab2200169 ib4500")

def test_leader_invalid_length(self):
        self.assertRaises(RecordLeaderInvalid, Leader, LEADER[:-1])

def test_str(self):
        leader = Leader(LEADER)
        self.assertEqual(str(leader), LEADER)

def test_leader_value(self):
        leader = Leader(LEADER)
        self.assertEqual(leader.leader, LEADER)

def test_setters_errors(self):
        leader = Leader(LEADER)
        for field, index, expected in FIELDS:
            value = random_string(len(expected) + 1)
            with self.assertRaises(BadLeaderValue):
                setattr(leader, field, value)

def test_setters(self):
        leader = Leader(LEADER)
        for field, index, expected in FIELDS:
            value = random_string(len(expected))
            leader[index] = value
            self.assertEqual(getattr(leader, field), value)
            value = random_string(len(expected))
            setattr(leader, field, value)
            self.assertEqual(leader[index], value)

def __init__(
        self,
        data="",
        to_unicode=True,
        force_utf8=False,
        hide_utf8_warnings=False,
        utf8_handling="strict",
        leader=" " * LEADER_LEN,
        file_encoding="iso8859-1",
    ):
        """Initialize a Record."""
        self.leader = Leader(leader[0:10] + "22" + leader[12:20] + "4500")
        self.fields = list()
        self.pos = 0
        self.force_utf8 = force_utf8
        if len(data) > 0:
            self.decode_marc(
                data,
                to_unicode=to_unicode,
                force_utf8=force_utf8,
                hide_utf8_warnings=hide_utf8_warnings,
                utf8_handling=utf8_handling,
                encoding=file_encoding,
            )
        elif force_utf8:
            self.leader = self.leader[0:9] + "a" + self.leader[10:]