'Adds path to the dict tracking paths belonging to this build phase.
If the path is already a member of this build phase, raises an exception.'

def _AddPathToDict(self, pbxbuildfile, path):

    if (path in self._files_by_path):
        raise ValueError(('Found    multiple    build    files    with    path    ' + path))
    self._files_by_path[path] = pbxbuildfile
