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Now we get to know functions with parameters. With
var give = function(input) {
  return input;
we define a function that simply returns the parameter input. Parameters are variables. With
var result = give('apple');
we call the function and pass it the argument 'apple'. The function will be executed. The argument 'apple' will be assigned to the parameter input. input gets the value 'apple'. The variable input is returned in the single code line of the function. This return is assigned to the variable result. Finally, result has the value 'apple'.


Write a function echo that also returns the passed parameter. echo('Greta') should return 'Greta' and echo('CO2') should return 'CO2'
var echo = function(sound) {
var echo = function(sound) {
  return sound;