def e( x, y, s ) :
    ''' Return the value of the expression x s y, where x and y are operands,
        and s is an arithmetic operator.
    '''

    # Example is x = 19.5, y = 5.25, and s1 can be +-*/ (multiplication is * and division is /)
    # We want to return the result of this operation x s y where x and y are numbers and s is the operator (+-*/)
    # A single = is assignment (ex. x = 2) and == is a logical operator that checks if two things are equal (evaluates
    # to True/False)
    # ex. 5 == 5 is True
    # ex. 2 == 5 is False
    # Conditionally check if s is a certain operator and evaluate the result based on if s == the operator
    if ( s == '+' ):    # Addition
        result = x + y
    elif ( s == '-' ): # Subtraction
        result = x - y
    elif ( s == '*' ): # Multiplication
        result = x * y
    elif ( s == '/' ): # Division
        result = x / y
    else:  # They gave us a bad operator like @
        result = None
    return result


''' DO NOT MODIFY THE BELOW CODE '''

if ( __name__ == '__main__' ) :
    import calc

    x1 = 19.5;		y1 =  5.25;		s1 = '+'
    x2 = 12.5;		y2 =  6.5;		s2 = '-'
    x3 = 12.5;		y3 =  4.5;		s3 = '*'
    x4 = 10.0;		y4 =  2.25;		s4 = '/'
    x5 = 1.0;		y5 = 5.0;		s5 = '@'

    r1 = calc.e( x1, y1, s1 );		print( x1, s1, y1, '=', r1 )

    r2 = calc.e( x2, y2, s2 );		print( x2, s2, y2, '=', r2 )

    r3 = calc.e( x3, y3, s3 );		print( x3, s3, y3, '=', r3 )

    r4 = calc.e( x4, y4, s4 );		print( x4, s4, y4, '=', r4 )

    r5 = calc.e( x5, y5, s5 );		print( x5, s5, y5, '=', r5 )