code: def disk_available():
      data = psutil.disk_usage("/").free / (1024 * 1024 * 1024)  # in GB
      system_metrics.append(
          Metric("DiskAvailable", data, "GB", dimension)
      )
  
file_path: serve/ts/metrics/system_metrics.py
imports: import logging
  import types
  from builtins import str
  import psutil
  from ts.metrics.dimension import Dimension
  from ts.metrics.metric import Metric
label_desc: Use image node_id 7 for calling a global function with example usage: disk_available() without return types