Nodes of different colours represent the following:
Solid arrows point from a procedure to one which it calls. Dashed
arrows point from an interface to procedures which implement that interface.
This could include the module procedures in a generic interface or the
implementation in a submodule of an interface in a parent module.
Where possible, edges connecting nodes are
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Module Procedures
private elemental function trim_string(string) result(trimmed_string)
Returns the character sequence hold by the string without trailing spaces.