docs: def nested_join(array, o_str= '{', c_str= '}'):
      '''
          Builds a string out of a given nested list.
          Args    :
              array   : An array retruned by pyparsing nestedExpr.
              o_str   : Opening str.
              c_str   : Closing str.
      '''
      result = ''
      for x in array :
          if type(x) == type([])  :
              result  +=o_str+ nested_join(x)+ c_str
          else                    :
              result  +=x
      return result