code: def get_previous_version_tag(version):
      """
      Get the version of the previous release
      """
      # We try, probably too hard, to portably get the number of the previous
      # release of SymPy. Our strategy is to look at the git tags.  The
      # following assumptions are made about the git tags:
  
      # - The only tags are for releases
      # - The tags are given the consistent naming:
      #    sympy-major.minor.micro[.rcnumber]
      #    (e.g., sympy-0.7.2 or sympy-0.7.2.rc1)
      # In particular, it goes back in the tag history and finds the most recent
      # tag that doesn't contain the current short version number as a substring.
      shortversion = get_sympy_short_version(version)
      curcommit = "HEAD"
      while True:
          cmdline = f"git describe --abbrev=0 --tags {curcommit}"
          print(cmdline)
          curtag = check_output(cmdline.split()).decode("utf-8").strip()
          if shortversion in curtag:
              # If the tagged commit is a merge commit, we cannot be sure
              # that it will go back in the right direction. This almost
              # never happens, so just error
              cmdline = f"git rev-list --parents -n 1 {curtag}"
              print(cmdline)
              parents = (
                  check_output(cmdline.split())
                  .decode("utf-8")
                  .strip()
                  .split()
              )
              # rev-list prints the current commit and then all its parents
              # If the tagged commit *is* a merge commit, just comment this
              # out, and manually make sure `get_previous_version_tag` is correct
              # assert len(parents) == 2, curtag
              curcommit = (
                  curtag + "^"
              )  # The parent of the tagged commit
          else:
              print(
                  blue(
                      "Using {tag} as the tag for the previous "
                      "release.".format(tag=curtag)
                  )
              )
              return curtag
      sys.exit(red("Could not find the tag for the previous release."))
  
file_path: sympy/release/authors.py
imports: import os
  from pathlib import Path
  from subprocess import check_output
  import unicodedata
label_desc: Use image node_id 4 for calling a global function with example usage: get_previous_version_tag(version) and returns: curtag