Buffers input until the given predicate returns true for a given buffer state and value.
Emits all buffered values up until (and including) the value for which the predicate returns a truthy value.
Modifies the state based on the return value of the predicate.
If the predicate returns true for the given state and value, payload will be set
to the state's buffer plus the given value.
Buffers input until the given predicate returns true for a given buffer state and value. Emits all buffered values up until (and including) the value for which the predicate returns a truthy value.