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# PredicateBindings

A mapping from a predicates’s input variables to their values.

```
struct PredicateBindings
```

## Overview

If you define a custom predicate expression type, you must propagate the predicate’s bindings to its subexpressions.

If you define a custom predicate type, you must create an instance of this structure, populate it with the predicate’s variables, and propagate it throughout the expression tree.

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