class_docstr: Encapsulation of a request to Demisto to create an incident.
class_docstr_tok: ["Encapsulation","of","a","request","to","Demisto","to","create","an","incident","."]
code: def map_severity_string_to_severity_value(cls, severity_string):
      if not isinstance(severity_string, str):
          return cls.SEVERITY_UNKNOWN
  
      lc_severity_string = severity_string.lower()
      if lc_severity_string in {"info", "informational"}:
          return cls.SEVERITY_INFORMATIONAL
      if lc_severity_string == "low":
          return cls.SEVERITY_LOW
      if lc_severity_string in {"med", "medium"}:
          return cls.SEVERITY_MEDIUM
      if lc_severity_string == "high":
          return cls.SEVERITY_HIGH
      if lc_severity_string == "critical":
          return cls.SEVERITY_CRITICAL
  
      return cls.SEVERITY_UNKNOWN
  
imports: from collections import OrderedDict
  from streamalert.alert_processor.helpers import compose_alert
  from streamalert.alert_processor.outputs.output_base import OutputDispatcher, OutputProperty, StreamAlertOutput, OutputRequestFailure
  from streamalert.shared.logger import get_logger
label_desc: Use image node_id 12 for calling the DemistoCreateIncidentRequest obj's underlying member method code with example usage: obj.map_severity_string_to_severity_value(cls, severity_string) and returns: cls, cls, cls, cls, cls, cls, cls