Function eval_comparison_expression 

pub fn eval_comparison_expression(
    expr: &ComparisonExpression,
    observation: &Observation,
    store: Option<&ObjectStore>,
) -> bool

Evaluate a comparison expression against one observation using binding enumeration: each distinct referenced object-type is bound to one object of that type from the observation (or none); the expression matches if some binding makes the boolean tree true. This gives correct “same object” semantics for AND within an observation while staying cheap (observations are small).