def _parse_requirements(self, input):
results = []<EOL>for line in input:<EOL><INDENT>(package, version) = self._parse_line(line)<EOL>if package:<EOL><INDENT>results.append((package, version))<EOL><DEDENT><DEDENT>return tuple(results)<EOL>
Parse a list of requirements specifications.
            Lines that look like "foobar==1.0" are parsed; all other lines are
            silently ignored.

            Returns a tuple of tuples, where each inner tuple is:
                (package, version)