19. Implement circ_area
Now that you have fixed the header for circ_area, it is time to implement the function. Again, pay close attention to the specification. If you are having trouble understanding the specification, look at the test cases in tests.py. When you have implemented the function, test your answer with the test script. You should pass all tests (for now).
def circ_area(**kw): # The parameter is MISSING. Add it back.
"""
Returns the area of the specified circle, defined by the keywords in kwd
The area of a circle is PI r*r where r is the radius
The circle may be specified by 'radius' or 'diameter', but not both. This function
should intentionally crash (with an AssertionError) if neither 'radius' nor 'diameter'
are specified, or if they both are.
Any keyword arguments other than 'radius' or 'diameter' are ignored.
Examples:
circ_area(radius=3) returns approx 28.27433
circ_area(diameter=4) returns approx 12.56637
circ_area(radius=3,foo=20) returns approx 28.27433
circ_area() crashes with AssertionError
circ_area(radius=2,diameter=4) crashes with AssertionError
Parameter kwd: the function keyword arguments
Precondition: the arguments are all numbers (int or float)
"""
pass