missing word in "Building CPS" v 2.9.4

[Matt Wette]

The reference manual for 2.9.4, Section 9.4.4.3 titled "Building CPS", 
paragraph 2, has sentence starting:

"Construction is handled by a set of mutually builder macros:"
I think there is a missing word between "mutually" and "builder". No 
clue what it is.

Matt