Provide an option that the user can optionally select.
option(<variable> "<help_text>" [value])
Provides an option for the user to select as ON or OFF. If no initial <value> is provided, OFF is used. If <variable> is already set as a normal or cache variable, then the command does nothing (see policy CMP0077).
If you have options that depend on the values of other options, see the module help for CMakeDependentOption.
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Licensed under the BSD 3-clause License.
https://cmake.org/cmake/help/v3.19/command/option.html