diff --git a/prometheus_client/bridge/graphite.py b/prometheus_client/bridge/graphite.py
index 8cadbedc..b9764e3a 100755
--- a/prometheus_client/bridge/graphite.py
+++ b/prometheus_client/bridge/graphite.py
@@ -59,30 +59,30 @@ def __init__(self,
         self._timeout = timeout_seconds
         self._timer = _timer
 
-    def push(self, prefix: str = '') -> None:
+    def push(self, prefix: str = "") -> None:
         now = int(self._timer())
         output = []
 
-        prefixstr = ''
-        if prefix:
-            prefixstr = prefix + '.'
+        prefixstr = prefix + "." if prefix else ""
 
         for metric in self._registry.collect():
             for s in metric.samples:
+                labelstr = ""
                 if s.labels:
-                    if self._tags:
-                        sep = ';'
-                        fmt = '{0}={1}'
-                    else:
-                        sep = '.'
-                        fmt = '{0}.{1}'
+                    sep = ";"
+                    fmt = "{0}={1}"
+                    if not self._tags:
+                        sep = "."
+                        fmt = "{0}.{1}"
                     labelstr = sep + sep.join(
-                        [fmt.format(
-                            _sanitize(k), _sanitize(v))
-                            for k, v in sorted(s.labels.items())])
-                else:
-                    labelstr = ''
-                output.append(f'{prefixstr}{_sanitize(s.name)}{labelstr} {float(s.value)} {now}\n')
+                        [
+                            fmt.format(_sanitize(k), _sanitize(v))
+                            for k, v in sorted(s.labels.items())
+                        ]
+                    )
+                output.append(
+                    f"{prefixstr}{_sanitize(s.name)}{labelstr} {float(s.value)} {now}\n"
+                )
 
         conn = socket.create_connection(self._address, self._timeout)
         conn.sendall(''.join(output).encode('ascii'))
diff --git a/prometheus_client/metrics.py b/prometheus_client/metrics.py
index af512115..cf654e29 100644
--- a/prometheus_client/metrics.py
+++ b/prometheus_client/metrics.py
@@ -23,12 +23,7 @@
 
 
 def _build_full_name(metric_type, name, namespace, subsystem, unit):
-    full_name = ''
-    if namespace:
-        full_name += namespace + '_'
-    if subsystem:
-        full_name += subsystem + '_'
-    full_name += name
+    full_name = "_".join(filter(None, [namespace, subsystem, name]))
     if metric_type == 'counter' and full_name.endswith('_total'):
         full_name = full_name[:-6]  # Munge to OpenMetrics.
     if unit and not full_name.endswith("_" + unit):
diff --git a/prometheus_client/openmetrics/exposition.py b/prometheus_client/openmetrics/exposition.py
index 26f3109f..c91c993d 100644
--- a/prometheus_client/openmetrics/exposition.py
+++ b/prometheus_client/openmetrics/exposition.py
@@ -27,13 +27,13 @@ def generate_latest(registry):
             if metric.unit:
                 output.append(f'# UNIT {mname} {metric.unit}\n')
             for s in metric.samples:
+                labelstr = ''
                 if s.labels:
                     labelstr = '{{{0}}}'.format(','.join(
                         ['{}="{}"'.format(
                             k, v.replace('\\', r'\\').replace('\n', r'\n').replace('"', r'\"'))
                             for k, v in sorted(s.labels.items())]))
-                else:
-                    labelstr = ''
+                exemplarstr = ''
                 if s.exemplar:
                     if not _is_valid_exemplar_metric(metric, s):
                         raise ValueError(f"Metric {metric.name} has exemplars, but is not a histogram bucket or counter")
@@ -52,8 +52,6 @@ def generate_latest(registry):
                             labels,
                             floatToGoString(s.exemplar.value),
                         )
-                else:
-                    exemplarstr = ''
                 timestamp = ''
                 if s.timestamp is not None:
                     timestamp = f' {s.timestamp}'
diff --git a/prometheus_client/parser.py b/prometheus_client/parser.py
index dc8e30df..5a3f4c30 100644
--- a/prometheus_client/parser.py
+++ b/prometheus_client/parser.py
@@ -156,10 +156,8 @@ def build_metric(name: str, documentation: str, typ: str, samples: List[Sample])
             if name.endswith('_total'):
                 name = name[:-6]
             else:
-                new_samples = []
-                for s in samples:
-                    new_samples.append(Sample(s[0] + '_total', *s[1:]))
-                    samples = new_samples
+                new_samples = [Sample(s[0] + '_total', *s[1:]) for s in samples]
+                samples = new_samples
         metric = Metric(name, documentation, typ)
         metric.samples = samples
         return metric