code: def unregister(matcher):
      
      # If it's a string handle it like an alias
      if isinstance(matcher, text_types) and matcher in matchers:
          matcher = matchers[matcher]
  
      # Find all aliases associated to the matcher
      aliases = [k for k, v in matchers.iteritems() if v == matcher]
      for alias in aliases:
          del matchers[alias]
          # Clean up the normalized versions
          norms = [k for k, v in normalized.iteritems() if v == alias]
          for norm in norms:
              del normalized[norm]
  
      # Remove help docstring
      if matcher in helpmatchers:
          del helpmatchers[matcher]
  
      return len(aliases) > 0
docs: Unregister a matcher (or alias) from the registry