comefrom: <awangdev>125. Valid Palindrome_1.java
code: private boolean isValid(char c) {
  
          if (c >= '0' &&  c <= '9') return true;
          if (c >= 'a' &&  c <= 'z') return true;
          if (c >= 'A' &&  c <= 'Z') return true;
          return false;
      }
masked: private boolean var_0 ( char var_1 ) {
    if ( var_1 >= '0' && var_1 <= '9' ) return true ;
    if ( var_1 >= 'a' && var_1 <= 'z' ) return true ;
    if ( var_1 >= 'A' && var_1 <= 'Z' ) return true ;
    return false ;
  }
  