inc/class-Iac_User_Table.php
public function table_column( $content, $column, $user_id ) {

		if ( $this->column_name !== $column )
			return $content;

		// Unicode checkmark u2713: ✓
		$check = "\xe2\x9c\x93";
		// Unicode ballot X u2717: ✗
		$ballot_x = "\xe2\x9c\x97";

		$user_settings    = apply_filters( 'iac_get_user_settings', array(), $user_id );
		$subscribe_status = function( $type ) use ( $user_settings, $check, $ballot_x ) {
			$key = "inform_about_{$type}s";
			if ( ! isset( $user_settings[ $key ] ) ) {
				return $ballot_x;
			}

			return $user_settings[ $key ]
				? $check
				: $ballot_x;
		};

		$posts    = $subscribe_status( 'post' );
		$comments = $subscribe_status( 'comment' );
		$cell     =
			  __( 'Posts', 'inform_about_content' ) . ": $posts<br/>"
			. __( 'Comments', 'inform_about_content' ) . ": $comments";

		return $cell;
	}
public function table_column( $content, $column, $user_id ) {

		if ( $this->column_name !== $column )
			return $content;

		// Unicode checkmark u2713: ✓
		$check = "\xe2\x9c\x93";
		// Unicode ballot X u2717: ✗
		$ballot_x = "\xe2\x9c\x97";

		$user_settings    = apply_filters( 'iac_get_user_settings', array(), $user_id );
		$subscribe_status = function( $type ) use ( $user_settings, $check, $ballot_x ) {
			$key = "inform_about_{$type}s";
			if ( ! isset( $user_settings[ $key ] ) ) {
				return $ballot_x;
			}

			return $user_settings[ $key ]
				? $check
				: $ballot_x;
		};

		$posts    = $subscribe_status( 'post' );
		$comments = $subscribe_status( 'comment' );
		$cell     =
			  __( 'Posts', 'inform_about_content' ) . ": $posts<br/>"
			. __( 'Comments', 'inform_about_content' ) . ": $comments";

		return $cell;
	}
@wp-hook manage_users_custom_column

@param string $content
@param string $column
@param int    $user_id

@return string