class_docstr: Prepends a prefix on features names.
  
  Parameters
  ----------
  prefix
  
  Examples
  --------
  
  >>> from river import compose
  
  >>> x = {'a': 42, 'b': 12}
  >>> compose.Prefixer('prefix_').transform_one(x)
  {'prefix_a': 42, 'prefix_b': 12}
class_docstr_tok: ["Prepends","a","prefix","on","features","names",".","Parameters","--","--","--","--","--","prefix","Examples","--","--","--","--",">",">",">","from","river","import","compose",">",">",">","x","=","{","'","a","'",":","42",",","'","b","'",":","12","}",">",">",">","compose.Prefixer","(","'prefix_","'",")",".transform_one","(","x",")","{","'prefix_a","'",":","42",",","'prefix_b","'",":","12","}"]
code: def __init__(self, prefix: str):
      self.prefix = prefix
  
file_path: river/river/compose/renamer.py
imports: from __future__ import annotations
  from river import base
label_desc: Use image node_id 1 to create a new Prefixer object from inherited base classes: base with example: obj = Prefixer(prefix)