lel regions
===============================================

_Description_:
     This function returns 'true' if nested parallel regions are
     enabled, 'false' otherwise.  Here, 'true' and 'false' represent
     their language-specific counterparts.

     The state of nested parallel regions at startup depends on several
     environment variables.  If 'OMP_MAX_ACTIVE_LEVELS' is defined and
     is set to greater than one, then nested parallel regions will be
     enabled.  If not defined, then the value of the 'OMP_NESTED'
     environment variable will be followed if defined.  If neither are
     defined, then if either 'OMP_NUM_THREADS' or 'OMP_PROC_BIND' are
     defined with a list of more than one value, then nested parallel
     regions are enabled.  If none of these are defined, then nested
     parallel regions are disabled by default.

     Nested parallel regions can be enabled or disabled at runtime using
     'omp_set_nested', or by setting the maximum number of nested
     regions with 'omp_set_max_active_levels' to one to disable, or
     above one to enable.

_C/C++_:
     _Prototype_:   'int omp_get_nested(void);'

_Fortran_:
     _Interface_:   'logical function omp_get_nested()'

_See also_:
     *note omp_set_max_active_levels::, *note omp_set_nested::, *note
     OMP_MAX_ACTIVE_LEVELS::, *note OMP_NESTED::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.2.11.