message: Allow short transmission argument: position, velocity, or effort
  Automatically translate into full name, e.g. hardware_interface/PositionJointInterface
diff: <xacro:arg name="arm_id" default="panda" /> <!-- Name of this panda -->
  <xacro:arg name="hand" default="false" /> <!-- Should a franka_gripper be mounted at the flange?" -->
  <xacro:arg name="gazebo" default="false" /> <!-- Is the robot being simulated in gazebo?" -->
  - <xacro:arg name="transmission" default="hardware_interface/EffortJointInterface" /> <!-- The transmission that is used in the gazebo joints -->
  + <!-- The transmission type that is used to control arm joints in gazebo: position, velocity, or effort -->
  + <xacro:arg name="transmission" default="effort" />
  <xacro:property name="arm_id" value="$(arg arm_id)" />
  - <xacro:property name="transmission" value="$(arg transmission)" />
  <xacro:unless value="$(arg gazebo)">
  <!-- Create a URDF for a real hardware -->
  </joint>
  - <xacro:gazebo-joint joint="${arm_id}_joint1" transmission="${transmission}" />
  - <xacro:gazebo-joint joint="${arm_id}_joint2" transmission="${transmission}" />
  - <xacro:gazebo-joint joint="${arm_id}_joint3" transmission="${transmission}" />
  - <xacro:gazebo-joint joint="${arm_id}_joint4" transmission="${transmission}" />
  - <xacro:gazebo-joint joint="${arm_id}_joint5" transmission="${transmission}" />
  - <xacro:gazebo-joint joint="${arm_id}_joint6" transmission="${transmission}" />
  - <xacro:gazebo-joint joint="${arm_id}_joint7" transmission="${transmission}" />
  + <xacro:property name="transmission" value="$(arg transmission)" />
  + <!-- sanity check -->
  + <xacro:if value="${transmission.lower() not in ['position', 'velocity', 'effort']}" >
  + ${xacro.fatal("transmission:=" + transmission + " is not one of position, velocity, or effort")}
  + </xacro:if>
  + <!-- Unify transmission argument into title case and expand to full name -->
  + <xacro:property name="transmission" value="hardware_interface/${transmission.title()}JointInterface" lazy_eval="false" />
  + <xacro:gazebo-joint joint="$(arg arm_id)_joint1" transmission="${transmission}" />
  + <xacro:gazebo-joint joint="$(arg arm_id)_joint2" transmission="${transmission}" />
  + <xacro:gazebo-joint joint="$(arg arm_id)_joint3" transmission="${transmission}" />
  + <xacro:gazebo-joint joint="$(arg arm_id)_joint4" transmission="${transmission}" />
  + <xacro:gazebo-joint joint="$(arg arm_id)_joint5" transmission="${transmission}" />
  + <xacro:gazebo-joint joint="$(arg arm_id)_joint6" transmission="${transmission}" />
  + <xacro:gazebo-joint joint="$(arg arm_id)_joint7" transmission="${transmission}" />
  <xacro:transmission-franka-state arm_id="$(arg arm_id)" />
  <xacro:transmission-franka-model arm_id="$(arg arm_id)"
  