How to print variables on ROS using python?

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I am fairly new to ROS and I am working on a program that controls a robot arm. I am getting several errors related to various variables used in my nodes. I have been trying to find a way to print these variables like you do in python so that I can debug them, but I haven’t found a way to do so. I tried setting up a topic with the variables as the messages and a subscriber. I tried using rospy.loginfo and the console. I tried using plain print(). But none of these worked. I searched the ROS wiki tutorials but didn’t find anything. The code in question is supposed to control a robotic arm. Although the launch file runs a couple of other programs, I specifically want to print from one program called command_arm.py. The code for this program is:

(edit:) I created a node called printer which should print a simple string and then added it to the code. It still does not work. I ran a program with this same coding outside of ROS on my regular raspberry pi and it did work.

      #!/usr/bin/env python
    import rospy
    import traceback 
    import numpy as np
    # IMPORT the messages: 
    from sensor_msgs.msg import JointState
    from Adafruit_PWM_Servo_Driver import PWM
    #from std_msgs.msg import Float
    from std_msgs.msg import String

    #pins order is [base0 yaw, shoulder1 pitch, elbow2 pitch (relative to base), forearm3 roll, wrist4 pitch, finger5 roll]


    # PWM Controller set-up
    servo_pulse_frequency = 50
    servo_pulse_duration_us = 1.0e6/servo_pulse_frequency   # microseconds for each pulse
    servo_pulse_width_to_count_multiplier = 1./servo_pulse_duration_us*4095.0   # Counter is 12-bit, so 4096 levels (0-4095)

    # Initialise the PWM device using the default address
    pwm = PWM(0x40)   # Note if you'd like more debug output you can instead run:  pwm = PWM(0x40, debug=True)
    # Set the Frequency of all servo outputs
    pwm.setPWMFreq(servo_pulse_frequency)

    # Load parameters from rosparam to keep handy for the functions below: 
    # Matched lists of angles and microsecond commands
    map_angles_01 = np.radians(np.array(rospy.get_param('/rotational_angles_for_mapping_joint_01')))
    map_cmd_us_01 = np.array(rospy.get_param('/servo_cmd_us_for_mapping_joint_01'))
    map_angles_12 = np.radians(np.array(rospy.get_param('/rotational_angles_for_mapping_joint_12')))
    map_cmd_us_12 = np.array(rospy.get_param('/servo_cmd_us_for_mapping_joint_12'))
    map_angles_23 = np.radians(np.array(rospy.get_param('/rotational_angles_for_mapping_joint_23')))
    map_cmd_us_23 = np.array(rospy.get_param('/servo_cmd_us_for_mapping_joint_23'))
    map_angles_34 = np.radians(np.array(rospy.get_param('/rotational_angles_for_mapping_joint_34')))
    map_cmd_us_34 = np.array(rospy.get_param('/servo_cmd_us_for_mapping_joint_34'))
    map_angles_45 = np.radians(np.array(rospy.get_param('/rotational_angles_for_mapping_joint_45')))
    map_cmd_us_45 = np.array(rospy.get_param('/servo_cmd_us_for_mapping_joint_45'))
    map_angles_56 = np.radians(np.array(rospy.get_param('/rotational_angles_for_mapping_joint_56')))
    map_cmd_us_56 = np.array(rospy.get_param('/servo_cmd_us_for_mapping_joint_56'))


    # =============================================================================
    #   # No Publishers Needed 
    # =============================================================================

    def main(): 
        # =============================================================================
        #     # Launch a node called "command_arm"
        # =============================================================================
        rospy.init_node('command_arm', anonymous=False)
        rospy.init_node('printer', anonymous=False)
        # Set up subscriber that listens to "joint_states"
        sub_joint_states = rospy.Subscriber('/joint_states', JointState, command_arm)

        rospy.spin()

   def printer():
        print("something printed!!!!!!") 

    def command_arm(msg_in): 
        # unpack joint angle settings
        alpha0 = msg_in.position[0]
        beta1 = msg_in.position[1]
        beta2 = msg_in.position[2]
        beta2WORLD = beta1 + beta2
        gamma3 = msg_in.position[3]
        beta4 = msg_in.position[4]
        gamma5 = msg_in.position[5]    

        # Interpolate to find servo commands and send them
        cmd0 = interp_servo(map_angles_01, map_cmd_us_01, alpha0)
        command_servo(0,np.int(cmd0 ...