old_contents: from __future__ import division
  import sys
  import ctypes
  
  
  # Getting memory info, based on
  # http://stackoverflow.com/a/2017659/6621667 and
  # https://doeidoei.wordpress.com/2009/03/22/python-tip-3-checking-available-ram-with-python/
  class MemoryStatus(ctypes.Structure):
      _fields_ = [
          ("dwLength", ctypes.c_ulong),
          ("dwMemoryLoad", ctypes.c_ulong),
          ("ullTotalPhys", ctypes.c_ulonglong),
          ("ullAvailPhys", ctypes.c_ulonglong),
          ("ullTotalPageFile", ctypes.c_ulonglong),
          ("ullAvailPageFile", ctypes.c_ulonglong),
          ("ullTotalVirtual", ctypes.c_ulonglong),
          ("ullAvailVirtual", ctypes.c_ulonglong),
          ("sullAvailExtendedVirtual", ctypes.c_ulonglong),
      ]
  
      def __init__(self):
          self.dwLength = ctypes.sizeof(self)
          super(MemoryStatus, self).__init__()
  
  
  def platform_free_memory():
      if sys.platform == 'win32':
          memory_status = MemoryStatus()
          ctypes.windll.kernel32.GlobalMemoryStatusEx(ctypes.byref(memory_status))
          mem = memory_status.ullAvailPhys / (1024**3) # return in gigabytes
      else:
          memory_status = os.popen("free -m").readlines()
          if memory_status[0].split()[2].lower() == 'free':
              mem = int(memory_status[1].split()[3]) / 1024 # return in gigabytes
          else:
              raise ValueError('Unrecognized memory info')
      return mem
  
  
  def get_available_memory():
      try:
          import psutil # preferred way
          res = psutil.virtual_memory().available
      except ImportError:
          res = platform_free_memory()
      return res
  
new_contents: from __future__ import division
  import os
  import sys
  import ctypes
  
  
  # Getting memory info, based on
  # http://stackoverflow.com/a/2017659/6621667 and
  # https://doeidoei.wordpress.com/2009/03/22/python-tip-3-checking-available-ram-with-python/
  class MemoryStatus(ctypes.Structure):
      _fields_ = [
          ("dwLength", ctypes.c_ulong),
          ("dwMemoryLoad", ctypes.c_ulong),
          ("ullTotalPhys", ctypes.c_ulonglong),
          ("ullAvailPhys", ctypes.c_ulonglong),
          ("ullTotalPageFile", ctypes.c_ulonglong),
          ("ullAvailPageFile", ctypes.c_ulonglong),
          ("ullTotalVirtual", ctypes.c_ulonglong),
          ("ullAvailVirtual", ctypes.c_ulonglong),
          ("sullAvailExtendedVirtual", ctypes.c_ulonglong),
      ]
  
      def __init__(self):
          self.dwLength = ctypes.sizeof(self)
          super(MemoryStatus, self).__init__()
  
  
  def platform_free_memory():
      if sys.platform == 'win32':
          memory_status = MemoryStatus()
          ctypes.windll.kernel32.GlobalMemoryStatusEx(ctypes.byref(memory_status))
          mem = memory_status.ullAvailPhys / (1024**3) # return in gigabytes
      else:
          memory_status = os.popen("free -m").readlines()
          if memory_status[0].split()[2].lower() == 'free':
              mem = int(memory_status[1].split()[3]) / 1024 # return in gigabytes
          else:
              raise ValueError('Unrecognized memory info')
      return mem
  
  
  def get_available_memory():
      try:
          import psutil # preferred way
          res = psutil.virtual_memory().available
      except ImportError:
          res = platform_free_memory()
      return res
  
subject: fix os import error on linux for free system memory calculation