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
<tt>(o==null ? e==null : o.equals(e))</tt>.
@param o element whose presence in this deque is to be tested
@return {@code true} if this deque contains the specified element
@throws ClassCastException if the type of the specified element
is incompatible with this deque
(<a href="Collection.html#optional-restrictions">optional</a>)
@throws NullPointerException if the specified element is null and this
deque does not permit null elements
(<a href="Collection.html#optional-restrictions">optional</a>)
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 <tt>(o==null ? e==null : o.equals(e))</tt>.
@param o element whose presence in this deque is to be tested @return {@code true} if this deque contains the specified element @throws ClassCastException if the type of the specified element is incompatible with this deque (<a href="Collection.html#optional-restrictions">optional</a>) @throws NullPointerException if the specified element is null and this deque does not permit null elements (<a href="Collection.html#optional-restrictions">optional</a>)