# Ensure arg is valid

``

    assert  arg (anything)

Raises an exception if the argument is either nil or false.

Introduced in v2.8

## Examples

# Example 1
``
    assert true
    assert 1
    assert "foo"
    assert false
| ``
    # Simple assertions
    # As true is neither nil or false, this assertion passes
    # Similarly, 1 passes
    # As do string
    # This will raise an exception
# Example 2
``
    assert false, "oops"
| ``
    # Communicating error messages
    # This will raise an exception containing the message "oops"
# Example 3
``
    assert (1 + 1) == 2
    assert [:a, :b, :c].size == 3
| ``
    # More interesting assertions
    # Ensure that arithmetic is sane!
    # ensure lists can be correctly counted