def _init_param(f):
    # Return the __init__ parameter string for this field.  For
    # example, the equivalent of 'x:int=3' (except instead of 'int',
    # reference a variable set to int, and instead of '3', reference a
    # variable set to 3).
    if f.default is MISSING and f.default_factory is MISSING:
        # There's no default, and no default_factory, just output the
        # variable name and type.
        default = ''
    elif f.default is not MISSING:
        # There's a default, this will be the name that's used to look
        # it up.
        default = f'=_dflt_{f.name}'
    elif f.default_factory is not MISSING:
        # There's a factory function.  Set a marker.
        default = '=_HAS_DEFAULT_FACTORY'
    return f'{f.name}:_type_{f.name}{default}'