def install_pip(self, package, save=True, save_dev=False):
        """Installs a pip package.

        :param save: if `True`, pins the package to the Hydrogen requirements
            YAML file.
        :param save_dev: if `True`, pins the package as a development
            dependency to the Hydrogen requirements YAML file.
        :param return: a **single** :class:`Requirement` object, representing
            the installed version of the given package.
        """
        requirement = Requirement.coerce(package)
        click.echo("pip install " + requirement.package)
        cmd = envoy.run("pip install {}".format(str(requirement)))
        if cmd.status_code == 0:
            installed_packages = get_installed_pypackages()
            package = installed_packages[requirement.package]
            requirement.version = "=={}".format(package.version)
            if save:
                self.requirements["all"].add(requirement)
            if save_dev:
                self.requirements["dev"].add(requirement)
            if save or save_dev:
                self.requirements.save()
            return requirement
        else:
            fatal(cmd.std_err)
def log_row(self, row_category: str, row: List[int]):
        """Logs a confusion matrix row.

        Args:
          row_category: Category to which the row belongs.
          row: List of integers specifying the values for the row.

        Raises:
          ValueError: If row_category is not in the list of categories set in
            set_categories or size of the row does not match the size of
            categories.
        """
        if row_category not in self._categories:
            raise ValueError('Invalid category: {} passed. Expected one of: {}'.\
              format(row_category, self._categories))

        if len(row) != len(self._categories):
            raise ValueError('Invalid row. Expected size: {} got: {}'.\
              format(len(self._categories), len(row)))

        self._matrix[self._categories.index(row_category)] = row