code: function isValidPathCharacter(ch) {
    if (!ch) {
      return false
    }
  
    const sub = ['!', '$', '&', "'", '(', ')', '*', '+', ',', ';', '='].map(code)
    return concat(ALPHA, DIGIT, sub, code(':'), code('@')).indexOf(code(ch)) > -1
  }
docs: pchar       = unreserved / pct-encoded / sub-delims / ":" / "@" unreserved  = ALPHA / DIGIT / "-" / "." / "_" / "~" pct-encoded = "%" HEXDIG HEXDIG sub-delims  = "!" / "$" / "&" / "'" / "(" / ")" / "*" / "+" / "," / ";" / "="