def get_index_by_name(self, name):
for i in range(len(self.vertices)):<EOL><INDENT>if self.vertices[i].name == name:<EOL><INDENT>return i<EOL><DEDENT><DEDENT>raise ValueError('<STR_LIT>')<EOL>
Give the index associated with a given vertex name.

        :param name: the name of a vertex.
        :type name: string
        :rval index: index of the vertex.
        :rtype int: