code: def _parse_requirements(self, input):
          
  
          results = []
  
          for line in input:
              (package, version) = self._parse_line(line)
              if package:
                  results.append((package, version))
  
          return tuple(results)
docs: 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)