This package defines the command \perfectcut#1#2 which displays a bracket <#1||#2>. Various other delimiters are similarly defined (parentheses, square brackets ...). The effect of these commands is to let the delimiters grow according to the number of nested \perfectcommands (regardless of the size of the contents). The package was originally intended for solving a notational issue for direct-style continuation calculi in proof theory. For general use, the package also defines commands for defining other sorts of delimiters which will behave in the same way (see example in the documentation). The package also offers a robust reimplementation of \big, \bigg, etc.