Returns {@code true} if this deque contains the specified element.
More formally, returns {@code true} if and only if this deque contains
at least one element {@code e} such that {@code o == e}.
@param o object to be checked for containment in this deque
@return {@code true} if this deque contains the specified element
Returns {@code true} if this deque contains the specified element. More formally, returns {@code true} if and only if this deque contains at least one element {@code e} such that {@code o == e}.
@param o object to be checked for containment in this deque @return {@code true} if this deque contains the specified element