isDigit method
Implementation
bool isDigit(String c, bool isHex) =>
(c.codeUnitAt(0) >= '0'.codeUnitAt(0) &&
c.codeUnitAt(0) <= '9'.codeUnitAt(0) &&
!isHex) |
((((c.codeUnitAt(0) >= 'a'.codeUnitAt(0) &&
c.codeUnitAt(0) <= 'f'.codeUnitAt(0)) |
(c.codeUnitAt(0) >= '0'.codeUnitAt(0) &&
c.codeUnitAt(0) <= '9'.codeUnitAt(0)) |
(c.codeUnitAt(0) >= 'A'.codeUnitAt(0) &&
c.codeUnitAt(0) <= 'F'.codeUnitAt(0))) &&
isHex));