How to use [eq]

The reference page of eq has its arguments, constraints and declaration.

[eq] is the equality “operator” in Magic, and it requires two arguments, both of which will be evaluated as potential signals - And the result of evaluating [eq] will only be true if the values of these two arguments are exactly the same.

.src:int:5
eq
   get-value:x:@.src
   .:int:5