Removes the specified element from this set if it is present.
More formally, removes an element <tt>e</tt> such that
<tt>(o is null ? e is null : o.equals(e))</tt>,
if this set contains such an element. Returns <tt>true</tt> if
this set contained the element (or equivalently, if this set
changed as a result of the call). (This set will not contain the
element once the call returns.)
@param o object to be removed from this set, if present
@return <tt>true</tt> if the set contained the specified element
Removes the specified element from this set if it is present. More formally, removes an element <tt>e</tt> such that <tt>(o is null ? e is null : o.equals(e))</tt>, if this set contains such an element. Returns <tt>true</tt> if this set contained the element (or equivalently, if this set changed as a result of the call). (This set will not contain the element once the call returns.)
@param o object to be removed from this set, if present @return <tt>true</tt> if the set contained the specified element