code: def find_packages(
          self,
          name,  # type: str
          constraint=None,  # type: Union[VersionConstraint, str, None]
          extras=None,  # type: Union[list, None]
          allow_prereleases=False,  # type: bool
      ):  # type: (...) -> List[Package]
          
          if constraint is None:
              constraint = "*"
  
          if not isinstance(constraint, VersionConstraint):
              constraint = parse_constraint(constraint)
  
          if isinstance(constraint, VersionRange):
              if (
                  constraint.max is not None
                  and constraint.max.is_prerelease()
                  or constraint.min is not None
                  and constraint.min.is_prerelease()
              ):
                  allow_prereleases = True
  
          info = self.get_package_info(name)
  
          packages = []
  
          for version, release in info["releases"].items():
              if not release:
                  # Bad release
                  self._log(
                      "No release information found for {}-{}, skipping".format(
                          name, version
                      ),
                      level="debug",
                  )
                  continue
  
              try:
                  package = Package(name, version)
              except ParseVersionError:
                  self._log(
                      'Unable to parse version "{}" for the {} package, skipping'.format(
                          version, name
                      ),
                      level="debug",
                  )
                  continue
  
              if package.is_prerelease() and not allow_prereleases:
                  continue
  
              if not constraint or (constraint and constraint.allows(package.version)):
                  if extras is not None:
                      package.requires_extras = extras
  
                  packages.append(package)
  
          self._log(
              "{} packages found for {} {}".format(len(packages), name, str(constraint)),
              level="debug",
          )
  
          return packages
docs: Find packages on the remote server.