old_contents: import importlib
  import warnings
  import distutils.version as dv
  
  
  def check_versions(minimum_versions):
      """Raises an ImportError if a dependent package is not installed
      and at the required version number, or provides a warning if the
      version of the dependent package cannot be found."""
  
      for module_name in minimum_versions.keys():
          minimum_version = dv.LooseVersion(minimum_versions[module_name])
  
          try:
              module = importlib.import_module(module_name)
              module_version = dv.LooseVersion(module.__version__)
          except ImportError:
              raise ImportError(f"Unable to import {module_name} while "
                                "importing PlasmaPy.") from None
          except AttributeError:  # coveralls: ignore
              warnings.warn(f"{module_name} version {minimum_version.vstring} "
                            "is required for PlasmaPy.  However, the version of "
                            f"{module_name} could not be determined to check if "
                            "this requirement is met.")
          else:
              if minimum_version > module_version:
                  raise ImportError(
                      f"{module_name} {minimum_version} or newer is required "
                      "for PlasmaPy. The currently installed version is "
                      f"{module_version}.") from None
  
new_contents: import importlib
  import warnings
  import distutils.version as dv
  from .exceptions import PlasmaPyWarning
  
  
  def check_versions(minimum_versions):
      """
      Raise an `ImportError` if a dependent package is not installed and
      at the required version number, or issue a
      `~plasmapy.utils.PlasmaPyWarning` if the version of the dependent
      package cannot be found.
      """
  
      for module_name in minimum_versions.keys():
          minimum_version = dv.LooseVersion(minimum_versions[module_name])
  
          try:
              module = importlib.import_module(module_name)
              module_version = dv.LooseVersion(module.__version__)
          except ImportError:
              raise ImportError(
                  f"Unable to import {module_name} while importing PlasmaPy.") from None
          except AttributeError:  # coveralls: ignore
              warnings.warn(
                  f"{module_name} version {minimum_version.vstring} "
                  "is required for PlasmaPy.  However, the version of "
                  f"{module_name} could not be determined to check if "
                  "this requirement is met.", PlasmaPyWarning)
          else:
              if minimum_version > module_version:
                  raise ImportError(
                      f"{module_name} {minimum_version} or newer is required "
                      "for PlasmaPy. The currently installed version is "
                      f"{module_version}.") from None
  
subject: Update ReST formatting in import_helpers.py