$19.$ 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 $28\mathrm{.}27433$

circ$\_$area$($diameter$=4)$ returns approx $12\mathrm{.}56637$

circ$\_$area$($radius$=3,$foo$=20)$ returns approx $28\mathrm{.}27433$

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