+
+ LilyPond is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ LilyPond is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with LilyPond. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+/*
+ Note that several internal functions have a calc_beam bool argument.
+ This argument means: "If set, acknowledge the fact that there is a beam
+ and deal with it. If not, give me the measurements as if there is no beam."
+ Most pure functions are called WITHOUT calc_beam, whereas non-pure functions
+ are called WITH calc_beam.
+
+ The only exception to this is ::pure_height, which calls internal_pure_height
+ with "true" for calc_beam in order to trigger the calculations of other
+ pure heights in case there is a beam. It passes false, however, to
+ internal_height and internal_pure_height for all subsequent iterations.