Pattern decompositions

The indentation of pattern-decomposition code should parallel the level of nesting it is matching in the target code.

Here is an example:

pattern assignToHexFortyTwo {
    assignmentOperator {
        .targetExpression == variableReference;
        .sourceExpression == intLiteral {
            .value == 42;
            .base == `hexadecimal`
        }
    }
};