ASTTYPES = {}
ASTTYPES[ast.Num] = lambda x: x.n
ASTTYPES[ast.NameConstant] = lambda x: x.value
ASTTYPES[ast.Name] = lambda x: x.id
ASTTYPES[ast.Str] = lambda x: x.s
ASTTYPES[ast.Tuple] = lambda x: tuple([ASTTYPES[type(y)](y) for y in x.elts])
ASTTYPES[ast.Attribute] = lambda x: ASTTYPES[type(x.value)](x.value)+'.'+x.attr
ASTTYPES[ast.List] = lambda x: str([ASTTYPES[type(y)](y) for y in x.elts])
ASTTYPES[ast.Bytes] = lambda x: x.s
ASTTYPES[ast.Call] = lambda x: (ASTTYPES[type(x.func)](x.func)+
                                '('+', '.join([str(ASTTYPES[type(y)](y)) for y in x.args])+')')
ASTTYPES[ast.UnaryOp] = lambda x: x.operand.n*-1
ASTTYPES[ast.Dict] = lambda x: dict((ASTTYPES[type(x.keys[y])](x.keys[y]),
                                     ASTTYPES[type(x.values[y])](x.values[y]))
                                    for y in range(0, len(x.keys)))
ASTTYPES[ast.Set] = lambda x: str(set([ASTTYPES[type(y)](y) for y in x.elts]))
TYPES = ['str', 'list', 'tuple', 'int', 'float', 'None', 'bool', 'False',
         'True', 'bytes', 'bytearray']

def get_sign(astfunc):
    '''
    Get signature of given ast.FunctionDef.
    '''
    args = astfunc.args.args
    defaults = []
    for value in astfunc.args.defaults:
        try:
            defaults.append('='+str(ASTTYPES[type(value)](value)))
        except KeyError:
            defaults.append('')
    defaults = list(reversed(defaults))
    while len(defaults) != len(args):
        defaults.append('')
    defaults = list(reversed(defaults))
    result = ', '.join([x.arg+defaults[index] for index, x in enumerate(args)])
    return html.escape(result)