code: def _warn_for_string_literal(csource):
      if '"' not in csource:
          return
      for line in csource.splitlines():
          if '"' in line and not line.lstrip().startswith("#"):
              import warnings
  
              warnings.warn(
                  "String literal found in cdef() or type source. "
                  "String literals are ignored here, but you should "
                  "remove them anyway because some character sequences "
                  "confuse pre-parsing."
              )
              break
  
imports: from .None import model
  from .commontypes import COMMON_TYPES, resolve_common_type
  from .error import FFIError, CDefError
  import weakref, re, sys
label_desc: Use image node_id 5 for calling a global function with example usage: _warn_for_string_literal(csource) without return types