To improve the readability of large numbers 
    em(digit separators)hi(digit separator) for integer and floating point
literals can be used. The digit separator is a single quote which may be
inserted between digits of such literals to enhance human
readability. Multiple digit separators may be used, but only one separator can
be inserted between successive digits. E.g.,
        verb(    1'000'000
    3.141'592'653'589'793'238'5
    ''123       // won't compile
    1''23       // won't compile either)

