def coerce(cls, string):
        """Create a :class:`Requirement` object from a given package spec."""
        match = re.match(cls.spec_regex, string)
        if not match:
            raise InvalidRequirementSpecError("could not parse requirement")
        package = match.group(1)
        if all(match.group(2, 3)):
            version = "".join(match.group(2, 3))
        else:
            version = None
        return cls(package, version)
def remove_attributes(self, model):
        """
        Removes the x and y attributes which were added by the forward handles
        Recursively searches for non-container layers
        """
        for child in model.children():
            if 'nn.modules.container' in str(type(child)):
                self.remove_attributes(child)
            else:
                try:
                    del child.x
                except AttributeError:
                    pass
                try:
                    del child.y
                except AttributeError:
                    pass