def env_get(context):
    """Get $ENVs into the pypyr context.

    Context is a dictionary or dictionary-like. context is mandatory.

    context['env']['get'] must exist. It's a dictionary.
    Values are the names of the $ENVs to write to the pypyr context.
    Keys are the pypyr context item to which to write the $ENV values.

    For example, say input context is:
        key1: value1
        key2: value2
        pypyrCurrentDir: value3
        env:
            get:
                pypyrUser: USER
                pypyrCurrentDir: PWD

    This will result in context:
        key1: value1
        key2: value2
        key3: value3
        pypyrUser: <<value of $USER here>>
        pypyrCurrentDir: <<value of $PWD here, not value3>>
    """
    get = context['env'].get('get', None)

    exists = False
    if get:
        logger.debug("start")

        for k, v in get.items():
            logger.debug(f"setting context {k} to $ENV {v}")
            context[k] = os.environ[v]

        logger.info(f"saved {len(get)} $ENVs to context.")
        exists = True

        logger.debug("done")
    return exists