class_docstr: Line-search-step update modifier, which performs a line search on the update step returned by
  the given optimizer to find a potentially superior smaller step size
  (specification key: `linesearch_step`).
  
  Args:
      optimizer (specification): Optimizer configuration
          (<span style="color:#C00000"><b>required</b></span>).
      max_iterations (parameter, int >= 1): Maximum number of line search iterations
          (<span style="color:#C00000"><b>required</b></span>).
      backtracking_factor (parameter, 0.0 < float < 1.0): Line search backtracking factor
          (<span style="color:#00C000"><b>default</b></span>: 0.75).
      name (string): (<span style="color:#0000C0"><b>internal use</b></span>).
      arguments_spec (specification): <span style="color:#0000C0"><b>internal use</b></span>.
code: def initialize_given_variables(self, *, variables):
      super().initialize_given_variables(variables=variables)
  
      self.line_search.complete_initialize(
          arguments_spec=self.arguments_spec,
          values_spec=self.variables_spec,
      )
  
file_path: tensorforce/tensorforce/core/optimizers/linesearch_step.py
imports: import tensorflow
  from tensorforce import TensorforceError
  from tensorforce.core import TensorDict, TensorSpec, TensorsSpec, tf_function, tf_util
  from tensorforce.core.optimizers import UpdateModifier
  from tensorforce.core.optimizers.solvers import solver_modules
label_desc: Use image node_id 2 for calling the LinesearchStep obj's underlying member method code with example usage: obj.initialize_given_variables() without return types