Return a string representing a callable.

    It is executed as if it would have been declared on the prompt.

    >>> def foo(arg1, arg2, arg3='val1', arg4='val2', *args, **argd):
    ...     pass
    >>> get_callable_signature_as_string(foo)
    def foo(arg1, arg2, arg3='val1', arg4='val2', *args, **argd)

    :param the_callable: the callable to be analyzed.
    :type the_callable: function/callable.
    :return: the signature.

def get_callable_signature_as_string(the_callable):
    """Return a string representing a callable.

    It is executed as if it would have been declared on the prompt.

    >>> def foo(arg1, arg2, arg3='val1', arg4='val2', *args, **argd):
    ...     pass
    >>> get_callable_signature_as_string(foo)
    def foo(arg1, arg2, arg3='val1', arg4='val2', *args, **argd)

    :param the_callable: the callable to be analyzed.
    :type the_callable: function/callable.
    :return: the signature.
    """
    args, varargs, varkw, defaults = inspect.getargspec(the_callable)
    tmp_args = list(args)
    args_dict = {}
    if defaults:
        defaults = list(defaults)
    else:
        defaults = []
    while defaults:
        args_dict[tmp_args.pop()] = defaults.pop()

    while tmp_args:
        args_dict[tmp_args.pop()] = None

    args_list = []
    for arg in args:
        if args_dict[arg] is not None:
            args_list.append("%s=%s" % (arg, repr(args_dict[arg])))
        else:
            args_list.append(arg)

    if varargs:
        args_list.append("*%s" % varargs)

    if varkw:
        args_list.append("**%s" % varkw)

    args_string = ', '.join(args_list)

    return "def %s(%s)" % (the_callable.__name__, args_string)