Parse compositor specifications, returning a list Compositors

def parse(cls, line, ns={}):
        """
        Parse compositor specifications, returning a list Compositors
        """
        definitions = []
        parses  = [p for p in cls.compositor_spec.scanString(line)]
        if len(parses) != 1:
            raise SyntaxError("Invalid specification syntax.")
        else:
            e = parses[0][2]
            processed = line[:e]
            if (processed.strip() != line.strip()):
                raise SyntaxError("Failed to parse remainder of string: %r" % line[e:])

        opmap = {op.__name__:op for op in Compositor.operations}
        for group in cls.compositor_spec.parseString(line):

            if ('mode' not in group) or group['mode'] not in ['data', 'display']:
                raise SyntaxError("Either data or display mode must be specified.")
            mode = group['mode']

            kwargs = {}
            operation = opmap[group['op']]
            spec = ' '.join(group['spec'].asList()[0])

            if  group['op'] not in opmap:
                raise SyntaxError("Operation %s not available for use with compositors."
                                  % group['op'])
            if  'op_settings' in group:
                kwargs = cls.todict(group['op_settings'][0], 'brackets', ns=ns)

            definition = Compositor(str(spec), operation, str(group['value']), mode, **kwargs)
            definitions.append(definition)
        return definitions