RAM: implemented magic method __lt__ for ASTNode to fix issues
    #88 and #209. The following test code works now, as does the test suite.
    import numexpr as ne
    a = 1 + 3j; b = 5.0
    ne.evaluate( 'a*2 + 15j - b' )

def getConstants(ast):
    '''
    RAM: implemented magic method __lt__ for ASTNode to fix issues
    #88 and #209. The following test code works now, as does the test suite.
    import numexpr as ne
    a = 1 + 3j; b = 5.0
    ne.evaluate( 'a*2 + 15j - b' )
    '''
    constants_order = sorted( ast.allOf('constant') )
    constants = [convertConstantToKind(a.value, a.astKind)
                 for a in constants_order]
    return constants_order, constants