Test if the specified key exists. The command returns true if the key exists, otherwise false is
returned. Note that even keys set with an empty string as value will return true. Time
complexity: O(1)
@param key
@return bool reply, true if the key exists, otherwise false
Test if the specified key exists. The command returns true if the key exists, otherwise false is returned. Note that even keys set with an empty string as value will return true. Time complexity: O(1) @param key @return bool reply, true if the key exists, otherwise false