Memcached::prepend() prepends the given
value string to the value of an existing item. The
reason that value is forced to be a string is
that prepending mixed types is not well-defined.
Note:
If the Memcached::OPT_COMPRESSION is enabled, the
operation will fail and a warning will be issued, because prepending
compressed data to a value that is potentially already compressed is not
possible.
Parameters
key
The key of the item to prepend the data to.
value
The string to prepend.
Return Values
Returns true on success or false on failure.
Returns null when compression is on.
Errors/Exceptions
Returns null and raises an E_WARNING when
compression is enabled.