Example of code generation in namedtuple https://github.com/python/cpython/blob/2.7/Lib/collections.py#L236

namedtuple.py

In [1]: from collections import namedtuple

In [2]: T = namedtuple("T","a b c",verbose=True)
class T(tuple):
    'T(a, b, c)'

    __slots__ = ()

    _fields = ('a', 'b', 'c')

    def __new__(_cls, a, b, c):
        'Create new instance of T(a, b, c)'
        return _tuple.__new__(_cls, (a, b, c))

    @classmethod
    def _make(cls, iterable, new=tuple.__new__, len=len):
        'Make a new T object from a sequence or iterable'
        result = new(cls, iterable)
        if len(result) != 3:
            raise TypeError('Expected 3 arguments, got %d' % len(result))
        return result

    def __repr__(self):
        'Return a nicely formatted representation string'
        return 'T(a=%r, b=%r, c=%r)' % self

    def _asdict(self):
        'Return a new OrderedDict which maps field names to their values'
        return OrderedDict(zip(self._fields, self))

    def _replace(_self, **kwds):
        'Return a new T object replacing specified fields with new values'
        result = _self._make(map(kwds.pop, ('a', 'b', 'c'), _self))
        if kwds:
            raise ValueError('Got unexpected field names: %r' % kwds.keys())
        return result

    def __getnewargs__(self):
        'Return self as a plain tuple.  Used by copy and pickle.'
        return tuple(self)

    __dict__ = _property(_asdict)

    def __getstate__(self):
        'Exclude the OrderedDict from pickling'
        pass

    a = _property(_itemgetter(0), doc='Alias for field number 0')

    b = _property(_itemgetter(1), doc='Alias for field number 1')

    c = _property(_itemgetter(2), doc='Alias for field number 2')