code: def _monomer_pattern_label(mp):
      
      site_strs = []
      for site, cond in mp.site_conditions.items():
          if isinstance(cond, tuple) or isinstance(cond, list):
              assert len(cond) == 2
              if cond[1] == WILD:
                  site_str = '%s_%s' % (site, cond[0])
              else:
                  site_str = '%s_%s%s' % (site, cond[0], cond[1])
          elif isinstance(cond, numbers.Real):
              continue
          else:
              site_str = '%s_%s' % (site, cond)
          site_strs.append(site_str)
      return '%s_%s' % (mp.monomer.name, '_'.join(site_strs))
docs: Return a string label for a MonomerPattern.