Turtle and Observer Command

average-of-frogs `[list of commands]`

Returns the numerical average of the [list of commands] when evaluated across all the turtles of breed frogs.

Note: If `[list of commands]` contains no numbers, an error occurs. If some of the `[list of commands]`, when evaluated, are not numbers, those values are ignored.

Note: When a turtle calls the command, it is not included as part of the calculation.

Examples:
average-of-frogs [speed] returns the average speed of all the turtles of breed frogs.

Related commands:
average-of-list average-of-patches