class_docstr: Wrap a FileSystem instance as a mutable wrapping.
  The keys of the mapping become files under the given root, and the
  values (which must be bytes) the contents of those files.
  
  Parameters
  ----------
  root: string
      prefix for all the files
  fs: FileSystem instance
  check: bool (=True)
      performs a touch at the location, to check for write access.
class_docstr_tok: ["Wrap","a","FileSystem","instance","as","a","mutable","wrapping",".","The","keys","of","the","mapping","become","files","under","the","given","root",",","and","the","values","(","which","must","be","bytes",")","the","contents","of","those","files",".","Parameters","--","--","--","--","--","root",":","string","prefix","for","all","the","files","fs",":","FileSystem","instance","check",":","bool","(","=True",")","performs","a","touch","at","the","location",",","to","check","for","write","access","."]
docstr: Does key exist in mapping?
docstr_tok: ["Does","key","exist","in","mapping","?"]
code: def __contains__(self, key):
      """Does key exist in mapping?"""
      return self.fs.exists(self._key_to_str(key))
  
imports: from collections.abc import MutableMapping
  from urllib.parse import urlparse
  from .local import LocalFileSystem
label_desc: Use image node_id 16 for calling the FSMap obj's underlying member method code with example usage: obj.__contains__(key) and returns: self