Simple example highlight execution of concurrent function calls (a top level main function and a generator function), yielding control back and forth and sending messages to each other.

generators_send_example.py

# helper class taken from https://www.geeksforgeeks.org/print-colors-python-terminal/
class colors:
    
    '''Colors class:reset all colors with colors.reset; two
    sub classes fg for foreground
    and bg for background; use as colors.subclass.colorname.
    i.e. colors.fg.red or colors.bg.greenalso, the generic bold, disable,
    underline, reverse, strike through,
    and invisible work with the main class i.e. colors.bold'''

    reset = '\033[0m'
    bold = '\033[01m'
    disable = '\033[02m'
    underline = '\033[04m'
    reverse = '\033[07m'
    strikethrough = '\033[09m'
    invisible = '\033[08m'

    class fg:
        black = '\033[30m'
        red = '\033[31m'
        green = '\033[32m'
        orange = '\033[33m'
        blue = '\033[34m'
        purple = '\033[35m'
        cyan = '\033[36m'
        lightgrey = '\033[37m'
        darkgrey = '\033[90m'
        lightred = '\033[91m'
        lightgreen = '\033[92m'
        yellow = '\033[93m'
        lightblue = '\033[94m'
        pink = '\033[95m'
        lightcyan = '\033[96m'

    class bg:
        black = '\033[40m'
        red = '\033[41m'
        green = '\033[42m'
        orange = '\033[43m'
        blue = '\033[44m'
        purple = '\033[45m'
        cyan = '\033[46m'
        lightgrey = '\033[47m'


def generator_function():
    while True:
        print(colors.fg.green, "GENERATOR\tAt start of while loop.")
        input()
        val = yield
        print(colors.fg.green, f"GENERATOR\tfunction executing now. received {val} sent from top level function")
        input()
        print(colors.fg.green, f"GENERATOR\tAbout to yield {val * 10}")
        input()
        yield val * 10
        print(colors.fg.green, f"GENERATOR\tresuming execution. Reached end of while loop.")
        input()


if __name__ == "__main__":
    # example code based upon https://www.bogotobogo.com/python/python_function_with_generator_send_method_yield_keyword_iterator_next.php
    generator = generator_function()
    value1 = next(generator)

    print(colors.fg.lightred, f"TOP\tlevel function received {value1} from generator. Calling next()")

    print(colors.fg.lightred, f"TOP\tlevel function sending 5.")
    return_value = generator.send(5)
    print(colors.fg.lightred, f"TOP\tlevel function executing again. Received {return_value} from generator")
    input()
    print(colors.fg.lightred, f"TOP\tlevel function calling NEXT.")
    value2 = next(generator)
    input()
    print(colors.fg.lightred, f"TOP\tlevel function sending 100")
    return_value2 = generator.send(100)
    print(colors.fg.lightred, f"TOP\tlevel main function received {value2} from generator. Calling next()")
    input()


''' Stdout below:

 GENERATOR	   At start of while loop.

 TOP	        level function received None from generator. Calling next()
 TOP	        level function sending 5.
 GENERATOR	    function executing now. received 5 sent from top level function

 GENERATOR	   About to yield 50

 TOP	        level function executing again. Received 50 from generator

 TOP	        level function calling NEXT.
 GENERATOR	   resuming execution. Reached end of while loop.

 GENERATOR	   At start of while loop.
'''