docs: def check_requirements(requirements, ignore=None):
  	"""
  	Parse requirements for package information to determine if all requirements
  	are met. The *requirements* argument can be a string to a requirements file,
  	a file like object to be read, or a list of strings representing the package
  	requirements.
  
  	:param requirements: The file to parse.
  	:type requirements: file obj, list, str, tuple
  	:param ignore: A sequence of packages to ignore.
  	:type ignore: list, tuple
  	:return: A list of missing or incompatible packages.
  	:rtype: list
  	"""
  	ignore = (ignore or [])
  	not_satisfied = []
  	working_set = pkg_resources.working_set
  	installed_packages = dict((p.project_name, p) for p in working_set)  # pylint: disable=E1133
  
  	if isinstance(requirements, str):
  		with open(requirements, 'r') as file_h:
  			requirements = file_h.readlines()
  	elif hasattr(requirements, 'readlines'):
  		requirements = requirements.readlines()
  	elif not isinstance(requirements, (list, tuple)):
  		raise TypeError('invalid type for argument requirements')
  
  	for req_line in requirements:
  		req_line = req_line.strip()
  		parts = re.match(r'^([\w\-]+)(([<>=]=)(\d+(\.\d+)*))?$', req_line)
  		if not parts:
  			raise ValueError("requirement '{0}' is in an invalid format".format(req_line))
  		req_pkg = parts.group(1)
  		if req_pkg in ignore:
  			continue
  		if req_pkg not in installed_packages:
  			try:
  				find_result = working_set.find(pkg_resources.Requirement.parse(req_line))
  			except pkg_resources.ResolutionError:
  				find_result = False
  			if not find_result:
  				not_satisfied.append(req_pkg)
  			continue
  		if not parts.group(2):
  			continue
  		req_version = distutils.version.StrictVersion(parts.group(4))
  		installed_pkg = installed_packages[req_pkg]
  		installed_version = re.match(r'^((\d+\.)*\d+)', installed_pkg.version)
  		if not installed_version:
  			not_satisfied.append(req_pkg)
  			continue
  		installed_version = distutils.version.StrictVersion(installed_version.group(0))
  		if parts.group(3) == '==' and installed_version != req_version:
  			not_satisfied.append(req_pkg)
  		elif parts.group(3) == '>=' and installed_version < req_version:
  			not_satisfied.append(req_pkg)
  		elif parts.group(3) == '<=' and installed_version > req_version:
  			not_satisfied.append(req_pkg)
  	return not_satisfied