code: def arbitrary(arg, where=None, how=None):
      
      return ops.Arbitrary(arg, how, where).to_expr()
docs: Selects the first / last non-null value in a column
  
      Parameters
      ----------
      arg : array expression
      where: bool, default None
      how : {'first', 'last', 'heavy'}, default 'first'
        Heavy selects a frequently occurring value using the heavy hitters
        algorithm. Heavy is only supported by Clickhouse backend.
  
      Returns
      -------
      arbitrary element : scalar type of caller