a module or a module name.

If no argument is given, the calling module is used.

A number of options may be provided as keyword arguments:

setUp
  A set-up function.  This is called before running the
  tests in each file. The setUp function will be passed a DocTest
  object.  The setUp function can access the test globals as the
  globs attribute of the test passed.

tearDown
  A tear-down function.  This is called after running the
  tests in each file.  The tearDown function will be passed a DocTest
  object.  The tearDown function can access the test globals as the
  globs attribute of the test passed.

globs
  A dictionary containing initial global variables for the tests.

optionflags
   A set of doctest option flags expressed as an integer.
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