code: def _string_replace(arg, pattern, replacement):
      
      return ops.StringReplace(arg, pattern, replacement).to_expr()
docs: Replaces each exactly occurrence of pattern with given replacement
      string. Like Python built-in str.replace
  
      Parameters
      ----------
      pattern : string
      replacement : string
  
      Examples
      --------
      >>> import ibis
      >>> table = ibis.table([('strings', 'string')])
      >>> result = table.strings.replace('aaa', 'foo')  # 'aaabbbaaa' becomes 'foobbbfoo'  # noqa: E501
  
      Returns
      -------
      replaced : string