old_contents: """ Meltdown Mitigation exercise """
  
  
  def is_criticality_balanced(temperature, neutrons_emitted):
      """Verify criticality is balanced.
  
      :param temperature: temperature value (integer or float)
      :param neutrons_emitted: number of neutrons emitted per second (integer or float)
      :return:  boolean True if conditions met, False if not
  
      A reactor is said to be critical if it satisfies the following conditions:
      - The temperature is less than 800.
      - The number of neutrons emitted per second is greater than 500.
      - The product of temperature and neutrons emitted per second is less than 500000.
      """
  
      pass
  
  
  def reactor_efficiency(voltage, current, theoretical_max_power):
      """Assess reactor efficiency zone.
  
      :param voltage: voltage value (integer or float)
      :param current: current value (integer or float)
      :param theoretical_max_power: power that corresponds to a 100% efficiency (integer or float)
      :return: str one of 'green', 'orange', 'red', or 'black'
  
      Efficiency can be grouped into 4 bands:
  
      1. green -> efficiency of 80% or more,
      2. orange -> efficiency of less than 80% but at least 60%,
      3. red -> efficiency below 60%, but still 30% or more,
      4. black ->  less than 30% efficient.
  
      The percentage value is calculated as
      (generated power/ theoretical max power)*100
      where generated power = voltage * current
      """
  
      pass
  
  
  def fail_safe(temperature, neutrons_produced_per_second, threshold):
      """Assess and return safety range.
  
      :param temperature: value of the temperature (integer or float)
      :param neutrons_produced_per_second: neutron flux (integer or float)
      :param threshold: threshold (integer or float)
      :return: str one of: 'LOW', 'NORMAL', 'DANGER'
  
      - `temperature * neutrons per second` < 40% of `threshold` == 'LOW'
      - `temperature * neutrons per second` +/- 10% of `threshold` == 'NORMAL'
      - `temperature * neutron per second` is not in the above-stated ranges ==  'DANGER'
      """
  
      pass
  
new_contents: """ Meltdown Mitigation exercise """
  
  
  def is_criticality_balanced(temperature, neutrons_emitted):
      """Verify criticality is balanced.
  
      :param temperature: temperature value (integer or float)
      :param neutrons_emitted: number of neutrons emitted per second (integer or float)
      :return:  boolean True if conditions met, False if not
  
      A reactor is said to be critical if it satisfies the following conditions:
      - The temperature is less than 800.
      - The number of neutrons emitted per second is greater than 500.
      - The product of temperature and neutrons emitted per second is less than 500000.
      """
  
      pass
  
  
  def reactor_efficiency(voltage, current, theoretical_max_power):
      """Assess reactor efficiency zone.
  
      :param voltage: voltage value (integer or float)
      :param current: current value (integer or float)
      :param theoretical_max_power: power that corresponds to a 100% efficiency (integer or float)
      :return: str one of 'green', 'orange', 'red', or 'black'
  
      Efficiency can be grouped into 4 bands:
  
      1. green -> efficiency of 80% or more,
      2. orange -> efficiency of less than 80% but at least 60%,
      3. red -> efficiency below 60%, but still 30% or more,
      4. black ->  less than 30% efficient.
  
      The percentage value is calculated as
      (generated power/ theoretical max power)*100
      where generated power = voltage * current
      """
  
      pass
  
  
  def fail_safe(temperature, neutrons_produced_per_second, threshold):
      """Assess and return safety range.
  
      :param temperature: value of the temperature (integer or float)
      :param neutrons_produced_per_second: neutron flux (integer or float)
      :param threshold: threshold (integer or float)
      :return: str one of: 'LOW', 'NORMAL', 'DANGER'
  
      - `temperature * neutrons per second` < 40% of `threshold` == 'LOW'
      - `temperature * neutrons per second` +/- 10% of `threshold` == 'NORMAL'
      - `temperature * neutrons per second` is not in the above-stated ranges ==  'DANGER'
      """
  
      pass
  
subject: Fix typo in docstring (#2593)