def __init__(self, envs=None, labels=None, line_envs=None, line_labels=None):
self.envs = envs or {}<EOL>self.labels = labels or {}<EOL>self.line_envs = line_envs or {}<EOL>self.line_labels = line_labels or {}<EOL>
Class representing current state of environment variables and labels.

:param envs: dict with variables valid for this line
    (all variables defined to this line)
:param labels: dict with labels valid for this line
    (all labels defined to this line)
:param line_envs: dict with variables defined on this line
:param line_labels: dict with labels defined on this line