feat: update read_header to skip comments and empty lines

Author: msto

fgpyo/util/metric.py

@@ -329,8 +329,27 @@ def fast_concat(*inputs: Path, output: Path) -> None:
             )
 
     @staticmethod
-    def read_header(reader: io.Reader) -> List[str]:
+    def read_header(
+        reader: io.Reader,
+        comment: str = "#",
+    ) -> List[str]:
         """
         Read the header from an open file.
+
+        Comment and empty lines will be ignored.
+
+        Args:
+            reader: An open, readable file
+            comment: The character which indicates the start of a comment line.
+
+        Returns:
+            A list of field names found in the header line.
         """
-        return reader.readline().rstrip("\r\n").split("\t")
+
+        for line in reader:
+            if not line.startswith(comment) and not line.strip() == "":
+                break
+        else:
+            raise ValueError("No header found")
+
+        return line.rstrip("\r\n").split("\t")