##concept
</pre>

In addition, there are versions of <tt>BOOST_CLASS_REQUIRE</tt> that
take more arguments, to handle concepts that include interactions
between two or more types. <tt>BOOST_CLASS_REQUIRE</tt> was not used
in the implementation of the BCCL concept checks because some
compilers do not implement template parameters of function pointer
type.

<!-- We decided not to go with this version since it is easier to misuse

To check the type parameters of class templates, we provide the
<tt>class_requir