docs: def v(self, version, max_version=None, **kwargs):
          """
          Returns either a single requirement version or a requirement version
          range depending on whether two arguments are supplied or one
  
          Parameters
          ----------
          version : str | Version
              Either a version of the requirement, or the first version in a
              range of acceptable versions
          """
          if not isinstance(version, Version):
              version = self.version_cls(self, version, **kwargs)
          # Return a version range instead of version
          if max_version is not None:
              if not isinstance(max_version, Version):
                  max_version = self.version_cls(self, max_version, **kwargs)
              version = VersionRange(version, max_version)
          return version