def _collapse_header(self, header):
out = []<EOL>for i, h in enumerate(header):<EOL><INDENT>if h.startswith(self._col_quals):<EOL><INDENT>out[-<NUM_LIT:1>].append(i)<EOL><DEDENT>else:<EOL><INDENT>out.append([i])<EOL><DEDENT><DEDENT>return out<EOL>
Combine header columns into related groups.