code: def merge_maps(m, base):
      
      
      for k in base.keys():
          if k not in m:
              m[k] = base[k]
docs: Merge in undefined map entries from given map.
      
      @param m: Map to be merged into.
      @type m: lems.util.Map
      
      @param base: Map to be merged into.
      @type base: lems.util.Map