Ansible prompt a variable in a task

There is the pause module to prompt for an input inside a task.

For example

    - hosts: localhost
      tasks:
        - pause:
            prompt: "Please enter the value for kernel.shmmax "
            echo: yes
          register: result
        - set_fact:
            shmmax: "{{ result.user_input }}"
        - debug:
            var: shmmax

gives (abridged)

    TASK [pause] 
    [pause]
    Please enter the value for kernel.shmmax :
    [ok: [localhost]
    TASK [set_fact]
    ok: [localhost]
    TASK [debug] 
    ok: [localhost] => {
        "shmmax": "new_kernel.shmmax_value"
    }

Notes

1. This part of the code from the question can't work because there is no module in the task

    - name: shmmax
          prompt: " Please enter the value for kernel.shmmax "
          private: false

Running such code would produce

    ERROR! Syntax Error while loading YAML.
      mapping values are not allowed in this context

2. A variable can be used in any task after it has been prompted for, registered, and declared with set_fact.