code: def _suggest_semantic_version(s):
      
      result = s.strip().lower()
      for pat, repl in _REPLACEMENTS:
          result = pat.sub(repl, result)
      if not result:
          result = '0.0.0'
  
      # Now look for numeric prefix, and separate it out from
      # the rest.
      #import pdb; pdb.set_trace()
      m = _NUMERIC_PREFIX.match(result)
      if not m:
          prefix = '0.0.0'
          suffix = result
      else:
          prefix = m.groups()[0].split('.')
          prefix = [int(i) for i in prefix]
          while len(prefix) < 3:
              prefix.append(0)
          if len(prefix) == 3:
              suffix = result[m.end():]
          else:
              suffix = '.'.join([str(i) for i in prefix[3:]]) + result[m.end():]
              prefix = prefix[:3]
          prefix = '.'.join([str(i) for i in prefix])
          suffix = suffix.strip()
      if suffix:
          #import pdb; pdb.set_trace()
          # massage the suffix.
          for pat, repl in _SUFFIX_REPLACEMENTS:
              suffix = pat.sub(repl, suffix)
  
      if not suffix:
          result = prefix
      else:
          sep = '-' if 'dev' in suffix else '+'
          result = prefix + sep + suffix
      if not is_semver(result):
          result = None
      return result
docs: Try to suggest a semantic form for a version for which
      _suggest_normalized_version couldn't come up with anything.