Implements lazy imports in the prometheus_api_client package's __init__.py(#293)

* Refactored __init__.py to improve imports and maintainability

Author: TMVKasiViswanath

prometheus_api_client/__init__.py

@@ -3,8 +3,21 @@
 __title__ = "prometheus-connect"
 __version__ = "0.6.0"
 
-from .prometheus_connect import *  # noqa F403
-from .metric import Metric  # noqa F401
-from .metrics_list import MetricsList  # noqa F401
-from .metric_snapshot_df import MetricSnapshotDataFrame  # noqa F401
-from .metric_range_df import MetricRangeDataFrame  # noqa F401
+from .exceptions import PrometheusApiClientException, MetricValueConversionError
+def __getattr__(name):
+    if name == "PrometheusConnect":
+        from .prometheus_connect import PrometheusConnect
+        return PrometheusConnect
+    elif name == "Metric":
+        from .metric import Metric
+        return Metric
+    elif name == "MetricsList":
+        from .metrics_list import MetricsList
+        return MetricsList
+    elif name == "MetricSnapshotDataFrame":
+        from .metric_snapshot_df import MetricSnapshotDataFrame
+        return MetricSnapshotDataFrame
+    elif name == "MetricRangeDataFrame":
+        from .metric_range_df import MetricRangeDataFrame
+        return MetricRangeDataFrame
+    raise AttributeError(f"module {__name__} has no attribute {name}")