def tokenize_exponent_literal
      advance # Pass the e/E
      advance if cchar == '+' or cchar == '-'
      advance until( /[0-9]/.match( cchar ).nil? )
      capture_token( :exp_literal )
    end
def tokenize_exponent_literal
      advance # Pass the e/E
      advance if cchar == '+' or cchar == '-'
      advance until( /[0-9]/.match( cchar ).nil? )
      capture_token( :exp_literal )
    end
Tokenize a literal with an exponent - e.g. 3.4E+22