How do I write multiple functions in one file?

I am writing my own Jenkins shared library. Currently my lib looks like this:

root
|
|- vars
   |---function1.groovy
   |---function2.groovy
   |---function3.groovy

Each function file contains a call() method and the code that it is executing. How can I combine all those functions in one file?

Solution

Put all functions into single file:

root
|
|- vars
   |---allFunctions.groovy

Rename functions from call() to:

function1(string) {
  echo "function1 - $string"
}

function2(string) {
  echo "function2 - $string"
}

Call them from different file (e.g. vars/buildRepo.groovy) as:

allFunctions.function1('Hello world via function1')
allFunctions.function2('Hello world via function2')

Call them from withing same file (e.g. vars/allFunctions.groovy) as:

function1('Hello world via function1')
function2('Hello world via function2')