The IN function searches for occurrences inside a container. The
    IN function is a special case of the CONTAINED_BY function. In its
    most common form, the function format is as follows:

    IN( <container>, <containee> )

    In this format, <container> and <containee> can be any legal query
    expression. The IN function returns all occurrences that match the
    <containee> expression as long as those occurrences are somewhere
    inside the container.

    Some examples will help you understand the IN function. The
    following picture applies to the examples that follow.

              A (module)
              +-------------------------+
              |                         |
              |  B (routine)            |
              |  +-------------------+  |
              |  |                   |  |
              |  |  C (routine)      |  |
              |  |  +-------------+  |  |
              |  |  |             |  |  |
              |  |  | D (variable)|  |  |
              |  |  |             |  |  |
              |  |  |             |  |  |
              |  |  +-------------+  |  |
              |  |                   |  |
              |  +-------------------+  |
              |                         |
              | E (variable)            |
              |                         |
              +-------------------------+

    Consider the following queries:

      1. FIND IN( A, *)
      2. FIND IN( B, D)
      3. FIND IN( A, SYMBOL_CLASS=ROUTINE and OCCURRENCE=DECLARATION)

    The first query returns B (a containee), C (a containee), D (a
    containee) and E (a containee). A is not returned because it is
    the container.

    The second query returns only D (the containee). C is not returned
    because it does not match the <containee> expression. B is not
    returned because it is the container.

    The third query returns all routine declarations inside A. In this
    case, B and C are returned.

    The IN function is a convenient way to limit a query to a
    particular container.

    The full format of the In function is as follows:

    IN( [END=<container>],
        [BEGIN=<containee>] )

    In this format, <container> and <containee> can be any legal query
    expression.