src/main/java/com/github/fge/grappa/parsers/BaseActions.java
public <E extends V> E popAs(@Nonnull final Class<E> c)
    {
        return c.cast(pop());
    }
public <E extends V> E popAs(@Nonnull final Class<E> c)
    {
        return c.cast(pop());
    }
Removes the value at the top of the value stack and casts it before
returning it

@param c the class to cast to
@param <E> type of the class
@return the current top value
@throws IllegalArgumentException the stack is empty

@see #pop()