class_docstr: A Progress bar for tracking progress of any task.
  
  Example:
  ```
  progress_bar = ProgressBar(
      max=100,
      label="Progress Bar",
      value=0,
      unit="%",
      metadata="0.1 items/s"
  )
  current.card.append(
      progress_bar
  )
  for i in range(100):
      progress_bar.update(i, metadata="%s items/s" % i)
  
  ```
  
  Parameters
  ----------
  max : int
      The maximum value of the progress bar.
  label : str, optional
      Optional label for the progress bar.
  value : int, optional
      Optional initial value of the progress bar.
  unit : str, optional
      Optional unit for the progress bar.
  metadata : str, optional
      Optional additional information to show on the progress bar.
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code: def update(self, new_value: int, metadata: str = None):
      self._value = new_value
      if metadata is not None:
          self._metadata = metadata
  
imports: from typing import Any, List, Optional, Union
  from .basic import LogComponent, ErrorComponent, ArtifactsComponent, TableComponent, ImageComponent, SectionComponent, MarkdownComponent
  from .card import MetaflowCardComponent
  from .convert_to_native_type import TaskToDict, _full_classname
  from .renderer_tools import render_safely
  import uuid
label_desc: Use image node_id 2 for calling the ProgressBar obj's underlying member method code with example usage: obj.update(new_value, metadata) without return types