''' Purpose: help with understanding that functions are first class
'''

def black() :
    print( "Black" )


def white() :
    print( "White" )

# we can pass functions as parameters into another function
# here, f is the placeholder for the NAME of the function we want to pass in
def run( f ) :
    print( 'f =', f )
    f()   # if we put parentheses after f, we are saying that we want to run this
          # parameter, f, as a FUNCTION --> this function doesn't need any parameters
    # this function run() invokes another function that we are going to pass in
# we'll see this happening in a little bit as we go into image manipulations 🦆
# this allows us to run several different functions with each invocation of run()
#   we can run one function that does several different things by passing in different functions
#   that can do different things

if ( __name__ == "__main__" ) :

    # run( 5 )      # 5 is an int, it is not a function --> program will blow up
    # black and white are names of some functions we define above
    run( black )
    run( print )
    run( white )