如何在yml文件中改变变量中的字符串？

variables:
  my_variable: "Hello, World!"

steps:
  - name: Print Variable
    script:
      - echo ${my_variable}

variables:
  my_variable: "Hello, World!"

steps:
  - name: Print Variable
    script:
      - echo ${my_variable.replace('World', 'Universe')}

variables:
  my_variable: "Hello, World!"

steps:
  - name: Print Variable
    script:
      - echo ${my_variable.substring(0, 3)}

variables:
  var1: "Hello"
  var2: "World"

steps:
  - name: Print Variable
    script:
      - echo ${var1.concat(var2)}